Acetylene derivatives hydrazones

Cyclic a,p-unsaturated ketones can be cleaved by treatment with base of their epoxy tosylhydrazone derivatives to give acetylenic ketones. The reaction can be applied to the formation of acetylenic aldehydes (R=H) by using the corresponding, 2,4-dinitrotosylhydrazone derivatives.Hydrazones (e.g., 47) prepared from... 

Although the addition of hydrazine and its derivatives to acetylenic ketones has been studied in considerable detail, their interaction with hydrazones and mono-alkylhydrazones is less well known. Yandovskii and Klindukhova (74ZOR730) have studied the reaction between hydrazones and alkylhydrazones of aliphatic ketones with dipropynylketones and showed that hydrazones of acetone, methyl-ethylketone, and cyclohexane easily add to one of the triple bonds of dipropynylketone to form 4-methyl-1,1,3-trialkyl-2,3-diaza-l,4-nonadien-7-yn-6-ones (yields... 

Natural (—)-actinidine (9a) is prepared from nepetalinic acid imide (262) via dichloropyridine (263) 403) and from iridodial (264) via bis (2,4-dinitrophe-nyl)hydrazone 404) or treatment with ferric ammonium sulfate (Scheme 19) 405). (+)-Actinidine (9b), the enantiomer of natural alkaloid, is synthesized from acid chloride 265, derived from (+)-pulegone, via vinylketone 267 (Scheme 20) 406). Racemic actinidine (9) is prepared by intramolecular cycloaddition of an acetylene across a pyrimidine ring in 5-(hept-5-yn-2-yl)-4,6-dihydroxypyrimidine (268) followed by chlorination and hydrogenation (Scheme 21) 407). 

Zinc chloride-doped natural phosphate was shown to have catalytic behavior in the 1,3-dipolar cycloadditions of nucleoside acetylenes with azides to form triazolonucleosides <99SC1057>. A soluble polymer-supported 1,3-dipolar cycloaddition of carbohydrate-derived 1,2,3-triazoles has been reported <99H(51)1807>. 2-Styrylchromones and sodium azide were employed in the synthesis of 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles <99H(51)481>. Lead(IV) acetate oxidation of mixed bis-aroyl hydrazones of biacetyl led to l-(a-aroyloxyarylideneamino)-3,5-dimethyl-l,2,3-triazoles <99H(51)599>. Reaction of 1-amino-3-methylbenzimidazolium chloride with lead(fV) acetate afforded l-methyl-l/f-benzotriazole <99BML961>. Hydrogenation reactions of some [l,2,3]triazolo[l,5-a]pyridines, [l,2,3]triazolo[l,5-a]quinolines, and [l,2,3]triazolo[l,5-a]isoquinolines were studied <99T12881>. 

It would be attractive from both mechanistic and preparative standpoints to obtain pyrroles by condensation of acetylene with ketoxime derivatives or analogs, e.g., their ethers or hydrazones, i.e., to realize the... 

Intramolecular insertion of olefins and acetylenes into the Zr-C bonds of zirconaaziridines can lead to annulation reactions. Livinghouse showed that alkyl-, silyl-, and aryl-substituted C-C multiple bonds readily insert into the Zr-C bonds of zirconaaziridines derived from the hydrazones 28 and 29, yielding cyclic products [28]. 

Ketone derivatives whose oxidations have wide applications in synthesis are hydrazones and vicinal dihydrazones. Hydrazones are transformed into diazo compounds, and vicinal dihydrazones are converted into acetylenes. By far the most widely used oxidant is yellow mercuric oxide... 

P. Quayle and co-workers utilized the Dotz benzannulation reaction for the synthesis of diterpenoid quinones." The authors developed a novel synthetic approach to 12-O-methyl royleanone using a simple vinyl chromium carbene complex along with a disubstituted oxygenated acetylene. The bicyclic hydrazone was converted to the corresponding vinyllithium derivative by the Shapiro reaction and then functionalized to give the desired crude Fischer chromium carbene complex. The benzannulation took place in refluxing THF with excellent regioselectivity, and the natural product was obtained in 37% overall yield from the hydrazone. 

Titanium-alkyne complexes Ti(Me3SiC=CC6Hi3)(OR)2, as well as the chiral complex derived from chloro-tris[(—)-menthoxo]titanium/2MgClPr1 and alkynes, react with carbonyl compounds to afford optically active allylic alcohols in up to 38% ee (Scheme 127).184 Introduction of two different electrophiles at each of the acetylenic terminal carbon atoms was possible in a regio- and stereoselective manner.45 Similarly, the titanacyclopentene compounds react with imines, metalloimines, or hydrazones under mild conditions to afford allylic amines or their derivatives in good to excellent yields (Scheme 128).258... 

The cleavage of an a.jS-epoxy-tosylhydrazone to give an acetylenic ketone has been employed to generate the 5(10)-seco-compound (386) best yields resulted from epoxidation of the tosylhydrazone of the 5(10)-en-6-one (385), rather than from first forming the epoxy-ketone. Aldol condensation of the derived saturated seco-3,10-dione (387) afforded the A-nor-B-homo-enone (388). The hydrazones derived from a, -epoxy-ketones and 2-phenyl- (389) or trans-23-diphenyl-l-aminoaziridines (390) undergo thermal fission (e.g. in refluxing DMF), also giving acetylenic aldehydes or ketones. ... 

Pyrazoles.—Formation. 3-Amino-4-ethylthio-5-methylpyrazole (311) is formed by the action of hydrazine on the nitrile MeBrC=C(SEt)CN. Acetylenic hydrazones R C=C-C(R )=NNHTos (R = H, Pr, or Ph R = H or Me) cyclize in the presence of potassium carbonate to the pyrazoles (312) via the iV-tosyl derivatives. Treatment of the (p-chlorophenyl)hydrazone (313) of ethyl 2-furylpyruvate with sulphuric acid affords only 10% of the expected ethyl 3-(2-furyl)indole-2-carboxyIate the main product is the pyrazole (314), formed presumably by way of the spiro-intermediate shown. ... 

Eschenmoser has published an extensive account of the fragmentation of ttjff-epoxy-ketones to alkynones numerous examples illustrate the course of thermolysis of hydrazones derived from ajS-epoxy-ketones and substituted aminoaziridines (Scheme 111). This preparatively useful method is also applicable to the preparation of acetylenic aldehydes. 

PerfluoroaIkyl-5-substituted-l//-pyrazoles 61 can be obtained in excellent yields by reaction of either perfluoroalkylacetylenes 59 [31] or A -aryl per(poly) fluoroalkyl phenyl acetylenic imines 60 [32] with hydrazine hydrate in EtOH (Scheme 18). The loss of two molecules of hydrogen fluoride in the former case, and arylamine in the latter, led to the final products. As it has been mentioned above, this strategy can be also applied for the preparation of polyfluorinated derivatives (see Scheme 3), by reaction of perfluoro-2-methyl-2-pentene with hydrazones [4] or arylhydrazines [5, 6] in a basic medium. 

Although all this could lead to the conclusion that acetylenes are great performers and the starting material of choice for directed selectivity in olefin synthesis, one should not forget the enol derivatives of ketones and also their hydrazones as usefiil starting materials [56]. 

Hydrazono-l,l,l-trifluoroalkan-2-ones 1030 are NNCC units that have found use in synthesis of pyridazine derivatives. In particular, they undergo dimerization upon treatment with trifluoroacetic acid to give pyridazines 1031 (Scheme 220) [621]. Mechanistic study of this transformation showed that a key step of the reaction is concerted [4+2] cycloaddition of protonated 1030 [622]. Pyridazines i.e. 1032 and 1033) were the products in other reactions of hydrazones 1030 with acetylene dicar-boxylates [621] and p-dicarbonyl compounds [623]. 

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